French Concordes stay grounded

Unlike the French fleet, BA's Concordes are still flying

Air France Concordes are to remain grounded for the time being after flight experts from France and Britain failed to agree extra safety measures following last week's Paris crash.

A spokesman for France's civil aviation authority said the ban would remain "until further notice" because new safety guidelines could not be drawn up until investigators had established the exact cause of the disaster.

Investigators have been unable to establish any scenario linking the elements of the accident

French civil aviation authority spokesman

The official inquiry team said it could take more than a year to do so.

The French transport minister suspended flights of Air France's five remaining Concordes after the 25 July tragedy, in which all 109 passengers and crew and four people on the ground were killed.

British Airways (BA), the only other airline to operate Concordes, has continued flights of its seven supersonic jets - despite a number of safety alerts over the weekend and a further problem on Tuesday.

In the latest incident BA confirmed that it had to replace a Concorde intended to operate the morning flight from London to New York.

Passengers were delayed 90 minutes after routine maintenance revealed that a number of minor adjustments were needed.

Prior to this month, Concorde's safety record was excellent

It has reiterated its position following the French ruling, telling BBC News Online it had "complete confidence" in Concorde.

The extra measures being reviewed in Paris had been designed to boost flagging public confidence in the grounded supersonic fleet, which Air France is keen to see take to the skies again.

The mayor of Gonesse, scene of the crash site near Roissy-Charles de Gaulle airport, and many of the town's inhabitants are among those who say the planes should stay on the ground until stringent safety checks are in place and the reasons for the crash are known.

Accident investigation

The investigators studying evidence from the crash said they had established that nothing was wrong before the plane took off.

Photographs and video tape clearly showed that the plane was on fire as it took off. One theory is that the aircraft's tyres blew out, ruptured the fuselage and caused the blaze

"The only certainties we have so far is that one or two tyres burst, [and] there was an intense fire," chief investigator Alain Monnier said on Monday.

Concorde tyres are one focus of the investigation

He said his inquiry was also sure there had been difficulties with the plane's landing gear and its engines.

As yet, however, the investigators say they cannot tell how these incidents are linked.

Earlier, they confirmed that a leak from a fuel tank - and not a failure of one of the engines as earlier thought - led to the fire which ravaged the plane.

BA alerts

The search for clues to last week's crash and ways of improving future safety has been taking place against the backdrop of a weekend of alerts to affect three separate BA Concorde flights.

Weekend scares

Sunday evening - "Fuel-like smell" prompts New York-bound flight to divert to Newfoundland

Sunday morning - Concorde grounded at Heathrow due to refuelling problems

Saturday evening - loud bang heard as flight lands at Heathrow

On Sunday evening, Flight 003 bound for New York was diverted to Gander in Newfoundland in Canada after passengers reported a smell of fuel.

Earlier on the same day, 51 passengers on the 1030 BST flight from Heathrow to New York were transferred to a standby aircraft because of a refuelling problem.

And on Saturday, a flight from New York was met by emergency services on the ground at Heathrow, after the pilot was alerted to a large bang - similar to a car engine backfiring - inside one of the engines.

BA described the action taken in all three cases as "routine safety procedure". It says it has found no evidence of a fuel leak on the diverted flight.